1. Field of the Invention
This invention relates generally to printers. More specifically, the present invention relates to a composite printing device which is usable both as a tape printer and as a portable printer.
2. Description of the Prior Art
Tape printers and portable printers are both known. The tape printer is most commonly used at a cashier of a shop, hotel or restaurant for printing out the calculated amount on a relatively narrow paper tape. On the other hand, the portable printer is used to print out necessary information only at a specific portion or portions of a relatively wide paper sheet.
In general, the tape printer comprises a case which accommodates a roll of paper tape, a feed mechanism for feeding a tape from the tape roll, a printing head for printing information onto the tape, and a guide for forcing the tape against the printing head, as disclosed in Japanese Utility Model Application No. 2-55670 (Filed: Oct. 15, 1988; Laid-open: Apr. 23, 1990) for example. However, the tape printer is disadvantageous in that it is applicable only to a relatively narrow tape.
The portable printer typically comprises a case which carries a printing head such as a thermal head, a feed mechanism for feeding an ink ribbon in contact with the printing head, and wheels for movably supporting the case, as disclosed for example in Japanese Utility Model Applications No. 63-170236 (Filed: Apr. 25, 1987; Laid-open: Nov. 7, 1988), No. 63-191037 (Filed: May 23, 1997; Laid-open: Dec. 8, 1998), and No. 63-94741 (Filed: Dec. 11, 1986; Laid-open: Jun. 18, 1988). The wheels include at least one drive wheel for automatically running on a desk top for example in synchronous relation to the feed speed of the ink ribbon while printing information on a paper sheet spread on the desk top.
Obviously, the applicability of the portable printer is not limited by the paper size itself. However, it is very inconvenient for the portable printer to print information on a continuous narrow tape and then cut off the printed tape portion from the remainder. More importantly, since the wheels of the portable printer cannot engage the narrow tape, it is difficult to synchronize the running speed (corresponding to the tape feed speed) of the printer with the transfer speed of the ink ribbon due to slips of the wheels relative to the desk top for example.
Thus, the prior art tape printer and portable printers, which are designed for different purposes, have their own applications.